Probe Fed Patch Antenna Design - simple

This tutorial tells you how to design a simple probe-fed patch antenna with simpleEMS. A probe-fed antenna is also called a coaxial-fed antenna.

Note

You must have simpleEMS and openEMS on your computer. See Installation.

Make a file with the name probe_fed_patch_antenna.py.

Import the modules

Import ProbeFedPatchParams, ProbeFedPatchAntenna, and setup_simulation from simpleEMS.

from simpleEMS import (
    ProbeFedPatchAntenna,
    ProbeFedPatchParams,
    setup_simulation,
)

ProbeFedPatchParams holds the parameters of the antenna and of the simulation.

See also

• simpleEMS.patch_antenna.ProbeFedPatchParams

ProbeFedPatchAntenna makes the antenna.

See also

• simpleEMS.patch_antenna.ProbeFedPatchAntenna

setup_simulation makes the CSXCAD geometry and the FDTD solver. It also sets the frequency range of the simulation.

See also

• simpleEMS.sim_tools.setup_simulation()

Set the parameters

params = ProbeFedPatchParams(
    resonant_freq=2.45e9,
    span_freq=0.5e9,
    substrate_thickness_mm=1.6,
    substrate_eps_r=4.4,
    substrate_tand=0.001,
    charac_imp=50,
)
params.probe_pos_mm = 4.501
params.patch_length_mm = 27.669

ProbeFedPatchParams holds the resonant frequency, the properties of the substrate, and the characteristic impedance of the antenna.

Set up the simulation

sim = setup_simulation(params)

setup_simulation prepares the FDTD solver and the CSXCAD geometry. It returns a SimSetup with the CSX, FDTD, and freqs attributes.

Build the antenna

patch = ProbeFedPatchAntenna(params, sim)
patch.print_and_save_params(params)
port = patch.build_probe_fed_patch_antenna()
patch.create_mesh()
nf2ff = patch.create_nf2ff(sim)
patch.add_field_dump(sim, params)
patch.write_and_show_structure(sim)

These commands build the antenna. Then they show the structure in AppCSXCAD. Close the AppCSXCAD window to continue. The antenna is now ready for the simulation.

Run the simulation

patch.run_simulation(sim)

This command runs the openEMS solver. Wait until the solver stops.

Show the results

sim_data = patch.compute_sim_data(sim, port)
nf2ff_3d_result = patch.compute_nf2ff_3d(nf2ff, params.resonant_freq)
patch.plot_s_param(sim_data.freqs, sim_data.s11)
patch.plot_smith_chart(sim_data.freqs, sim_data.s11)
patch.plot_vswr(sim_data.freqs, sim_data.vswr)
patch.plot_impedance(sim_data.freqs, sim_data.z11)
patch.plot_2d_directivity(nf2ff, params.resonant_freq)
patch.plot_2d_rad_pattern(nf2ff, params.resonant_freq)
patch.plot_3d_directivity(nf2ff_3d_result, params.resonant_freq)
patch.plot_3d_gain(nf2ff_3d_result, params.resonant_freq, sim_data.input_power)
patch.plot_3d_power(nf2ff_3d_result, params.resonant_freq)
patch.save_plots()
patch.show_plots()

These commands show the S11 curve, the VSWR, and the complex impedance. They also show the radiation pattern and the directivity in 2D and in 3D.

Export the results

You can write the model to different formats. Use these files in other tools, or send them to a PCB manufacturer.

patch.export_stl(sim)
patch.export_touchstone(
    sim_data.freqs,
    sim_data.s11,
    charac_imp=params.charac_imp,
)
patch.export_gerber(sim)

Complete script

The complete script is below. It designs the antenna, runs the simulation, and shows the results.

#!/usr/bin/env python3
"""Simple probe-fed patch antenna example at 2.45 GHz."""

# IMPORTS
from simpleEMS import (
    ProbeFedPatchAntenna,
    ProbeFedPatchParams,
    setup_simulation,
)

# IMPORTS

# PARAMS
params = ProbeFedPatchParams(
    resonant_freq=2.45e9,
    span_freq=0.5e9,
    substrate_thickness_mm=1.6,
    substrate_eps_r=4.4,
    substrate_tand=0.001,
    charac_imp=50,
)
params.probe_pos_mm = 4.501
params.patch_length_mm = 27.669
# PARAMS

# SETUP
sim = setup_simulation(params)
# SETUP

# BUILD
patch = ProbeFedPatchAntenna(params, sim)
patch.print_and_save_params(params)
port = patch.build_probe_fed_patch_antenna()
patch.create_mesh()
nf2ff = patch.create_nf2ff(sim)
patch.add_field_dump(sim, params)
patch.write_and_show_structure(sim)
# BUILD

# SIMULATE
patch.run_simulation(sim)
# SIMULATE

# PPROCESS
sim_data = patch.compute_sim_data(sim, port)
nf2ff_3d_result = patch.compute_nf2ff_3d(nf2ff, params.resonant_freq)
patch.plot_s_param(sim_data.freqs, sim_data.s11)
patch.plot_smith_chart(sim_data.freqs, sim_data.s11)
patch.plot_vswr(sim_data.freqs, sim_data.vswr)
patch.plot_impedance(sim_data.freqs, sim_data.z11)
patch.plot_2d_directivity(nf2ff, params.resonant_freq)
patch.plot_2d_rad_pattern(nf2ff, params.resonant_freq)
patch.plot_3d_directivity(nf2ff_3d_result, params.resonant_freq)
patch.plot_3d_gain(nf2ff_3d_result, params.resonant_freq, sim_data.input_power)
patch.plot_3d_power(nf2ff_3d_result, params.resonant_freq)
patch.save_plots()
patch.show_plots()
# PPROCESS

# EXPORT
patch.export_stl(sim)
patch.export_touchstone(
    sim_data.freqs,
    sim_data.s11,
    charac_imp=params.charac_imp,
)
patch.export_gerber(sim)
# EXPORT